Weighing system for a processing operation



Jan. 1, 1952 a. w. REILLY, JR

WEIGHING SYSTEM FOR A PROCESSING OPERATION Filed June 7, 1950 2 SHEETS-SHEET l In yen for flea/ye lflfiez?@ .77. 5 M 3% flzfarneys Jan. 1, 1952 e. w. REILLY, JR

WEIGHING "SYSTEM FOR A PROCESSING OPERATION 2 SHEETS-SHEET 2 Filed June 7, 1950 Patented Jan. 1, 1952 WEIGHING SYSTEM FOR A PROCESSING OPERATION George W. Reilly, Jr., Minneapolis, Minn., as-

signor to Wilson & Co., Inc., a corporation of Delaware Application June 7, 1950, Serial No. 166,708

6 Claims.

The present invention relates to weighing systems for use in processing operations wherein an article to be processed changes in weight during processing and wherein the desired change in weight during the processing is proportional to the original or base weight of the article prior to processing, irrespective of the value of that original weight. In the operation of the system of the present invention, the initiation and termination of the processing are controlled to secure the desired proportional change in weight during the processing operation.

In the prior copending applications of Lyman L. Campbell, Serial No. 17,520, filed March 27, 1948, and of Walter E. Moss et al., Serial No. 149,078, filed March 11, 1950, weighing systems are described wherein the article being processed may be, for example, a ham into which a certain percentage by weight of brine is to be pumped through the arteries of the ham. As a rule, hams for processing range in weight from about eight pounds to as much as twenty pounds and it is customary to add about 8% brine. In this particular application of such system, the weight of the article during processing is increased but, as explained in the above identified applications. the weighing systems described and claimed in these applications as well as the instant weighing system are adapted for use in processing any article wherein the weight is increased or decreased by a fixed percentage during processing.

As is more fully disclosed in said prior applications, the addition or subtraction of a constant proportion of a base weight lying within a range of base weights involves an exponential function. In the systems described in said applications, the exponential factor in the operating characteristics of the machine is present in the mechanical parts of the system and cooperates with the scale used for weighing the article during processing. Under certain conditions it may be desirable to reduce to a minimum the mechanical elements operatively associated with the scale and to incorporate the exponential operating characteristics of the system in anentirely different portion of the system. The present invention relates to such a weighing system wherein the weight responsive portion of the system need only generate a potential whose magnitude is a linear function of the weight of the article being processed. Thereafter, a system embodying the present invention utilizes such a potential so that a predetermined proportional change in such a potential due to a change in the weight of the article during processing will suflice for terminating or otherwise controlling the processing of the article.

In order to simplify the explanation, it will be assumed that the article being processed is a ham. In general, the scale first determines the base weight of the ham prior to processing and in 2 connection with this determination there is generated a potential having a value which is a linear function of the base weight of the ham.

A system embodying the present invention in general utilizes a potential having a value which is a linear function of the weight of the ham. The potential corresponding to the base weight of the ham prior to processing is utilized in a bridge which is brought to balance, an arm of the bridge being varied in proportion to the base weight potential. Thereafter, the bridge is unbalanced by a predetermined amount, and processing of the ham is initiated. The sense of the unbalance of the bridge is such that the increase in weight of the ham during pumping tends to bring the bridge into balance. When the bridge has regained bal-- ance, processing is terminated. Thus a bridge is utilized having a condition of balance corresponding to the base weight of the ham which condition will be referred to as the base weight balance. The second condition of bridge balance is when the ham has been pumped to the desired weight in which case the bridge balance may be considered as the process termination balance.

For a more complete description of the invention, reference will now be made to thedrawings wherein Fig. 1 is a diagrammatic showing of a generalized form of the invention. Fig. 2 shows a complete system illustrating one form which the invention may take.

Referring to Fig. 1, any suitable scale having platform l0, may be used, preferably the scale employed is one having a mechanical coupling between the platform and a movable element such that the movement of the latter is a linear function of the weight on the scale. Such couplings are conventional in scales for the operation of indicators, and hence are not shown. Scale III has ham l l disposed thereon, this ham having needle I2 clamped to an artery thereof in preparation for pumping. Needle I2 is connected by hose l3 to brine valve l4 controlling a supply of brine from a source not shown.

Mechanically coupled to scale platform I0 is generator l5 adapted to generate 01 control a potential having an amplitude which is a direct function of the weight of ham ll. Thus generator l5 may be a photoelectric system and amplifler and include a suitable light source and valve for modulating the amount of light in proportion to the weight of ham ll. Generator l5 may also be a potentiometer system similar to float-controlled systems used for registering gasoline in automobiles and liquids in tanks. Instead of the float in such a system, an arm mechanically coupled to platform III will be used for controlling or varying the amount of resistance. Other means for obtaining either direct or alternating potential having an amplitude which is a linear function of weight are well known and may be used as a generator.

Generator has one output terminal grounded and has its other output terminal connected to wire i'l. Wire H is connected to point it of bridge l3. Bridge l9 has resistance arm con nected between bridge point It and bridge point 22, the latter point being grounded. Between bridge point 22 and bridge point 23 is resistance arm 25, this resistor being variable. While resistor 25 may be manually varied, it is preferred to utilize Servo means 21 of any suitable type. Inasmuch as Servo mechanisms are well known and highly developed, a detailed description thereof is not essential. Bridge point 23 is connected by wire 23 to movable contact 29 of a switch. Movable contact 29 cooperates with fixed contacts 33 and 3i. Fixed contact at is connected through resistor 33 to bridge point 343 while fixed contact 36 of the switch is connected to wiper 35 cooperating with resistor 36 having one end connected to bridge point 33.

Between bridge point 34 and ground is connected any suitable source of potential 33, such source may be either alternating or direct. From bridge point 23 wire 40 goes to fixed contact ill of a switch having movable contact at. Movable contact 42 of the switch is connected by wire 43 to one terminal of Servo mechanism 23. The other terminal of Servo mechanism 2? is connected to movable contact 45 of a switch. Movable contact 45 cooperates with fixed contact 46, which contact is connected to wire ii. Wire i1 is also connected to control grid 43 of gas tube 49. Tube 49 has cathode 50 connected through bias resistor 5i to junction 52. From junction 52 wire 53 goes to and is connected to wire 43. From junction '52 a connection goes to winding 55 for operating brine valve i i. The other terminal of winding 55 is connected by wire 56 through any suitable source of alternating current such as transformer secondary 53 to anode 58 of tube 43.

The operation of the system is as follows: In order to put the system into operative condition, switch 42 is closed against contact M. Switches 29 and 45 remain in the position shown durin initial weighing of ham ii. Assuming that scale it has come to rest in a position corresponding to the base weight of ham i I, a certain potential will be impressed upon bridge point I8. Bridge point 34 will have a predetermined potential impressed thereon due to potential source 33. By varying bridge arm 25, it is possible to balance bridge l9 so that with the base weight potential on point ll! of the bridge there will be no difference in potential between points it and 23. It is understood that the arm between points 23 and 34 will include resistor 33. Now arm 25 is fixed in value during processing. Switches 2!] and 45 are operated. When switch 45 is operated, the Servo circuit is opened so that Servo mechanism 21 is inoperative. When switch 23 is operated, it is closed against contact 35 and resistor 33 is no longer in the bridge arm. Instead, resistor 33 forms part of the bridge system, the actual part of the resistor in the bridge arm being determined by the position of wiper 35. By suitable adjustment of the position of wiper 35 on resistor 35, it is possible to rearrange the ratio of resistances between bridge points 23 and 34 as one arm and either of the two arms connected to bridge point l8 so that a redetermined change in the resistance ratio is ob ined. Thus for example, assuming that the ratio of the resistance of the arm including 33 to thatof arm 20 is 1, then the resistance due to the active -portion of arm 35 over the resistance of arm 20'may be made 1.08 if an 8% increase in ham weight is to be desired. Movable wiper 35 of the potentiometer may be attached to a pointer moving over a scale indicating percentage increase or decrease, if desired in the article being processed.

With the bridge now in the processing position, it will be clear that a potential with respect to ground of bridge point i8 will have to vary by a predetermined proportion against the fixed potential from 38 in order to bring the bridge to a balanced condition. As shown in Fig. 1, upon unbalance of bridge is due to the initiation of processing and the change in the bridge arm from 33 to part of resistor 33, tube 39 may be arranged to either cut-in from a normally non-firing condition or cut-out from a normally firing condition to open valve it. It is clear that valve i4 may either be normally closed or normally open and that tube 43 may be either normally firing or normally blocked and that the change in the tube condition and valve condition due to initial unbalance of bridge i3 and subsequent balancing of the bridge may be accomplished in a manner well understood in the art.

It is apparent, therefore, that a bridge system is utilized wherein a potential varying in proportion to the weight of the ham is balanced against a fixed potential. This bridge is so arranged that one arm is varied to bring the bridge into balance for conditions corresponding to the base weight of the ham. Thereafter, this arm remains fixed and another arm is changed in a manner to unbalance the bridge to a predetermined degree. The unbalanced condition of the bridge requires a predetermined proportion of potential variation corresponding to weight variation of the ham in order to bring the bridge into final balanced condition corresponding to a termination of the processing.

Referring now to Fig. 2, the scale for weighing the ham has platform in upon which ham ii may rest. Ham H has needle i2 clamped properly in position and this needle may be supplied with brine from hose i3 and valve i4. Mechanically coupled to platform it is movable member i5a forming the rotor or movable part of a condenser, the coupling being preferably such that the movement of the member i5a is a linear function of the weight on the scale. The fixed plate of the condenser is indicated by i5b. Movable plate i5a is connected to ground through a suitable source of alternating current at a substantially constant frequency. The frequency of the source is such that variation of capacitance of the condenser over the operating range of the scale will result in a substantial change in the reactance of the condenser to the frequency selected. Thus, the frequency may be of the order of about one thousand cycles while the generator may be stable so that variation in capacitance in the condenser will have substantially no effect upon the impressed frequency.

Fixed plate 15b is connected by wire 65 through coupling condenser 66 to control grid 61 of vacuum tube amplifier 68. Resistors 69 and 10 are connected respectively between ground and the opposite sides of coupling condenser 66. Tube 68 has cathode 12 connected to ground through bias resistor I3. Tube 53 has anode I4 connected through load resistor E5 to wire 18 connected to the positive terminal of a suitable source of potential.

Anode 14 of tube 88 is also connected through coupling condenser 18 to control grid 19 of a second amplifier 80. Anode 8| of amplifier 80 is connected through load resistor 82 to wire 18 and is also connected through resistor 83to anode 14 of tube 88. Resistor 83 provides a negative feedback to tube 88 and stabilizes the stages. Ampliher 80 has cathode 85 connected to ground through bias resistor 88 while control grid 19 of this amplifier is also connected to ground through resistor 81.

Anode 8I is connected through coupling condenser 89 to junction 80 which junction is connected to point SI of a bridge. Connected between bridge point 3| and grounded bridge point 32 is resistor 93 forming one arm of the bridge. Connected between bridge point 8| and bridge point 35 are choke 88 and resistor 91. Between bridge point 92 and bridge point I are connected choke IM and variable resistor I02. Connected to bridge point I00 is one terminal of resistor I03. The other terminal of this resistor is connected to movable switch contact I04 cooperating with fixed contacts I and I08. Contact I05 of the switch is connected directly to bridge point 95. Contact I08 of the switch is connected through potentiometer I01 to bridge point 85.

Bridge point 85 is connected by wire I I0 to one terminal of transformer winding III, the other terminal II2 of this winding being grounded. Secondary III is coupled to primary winding II4 of a power transformer and is adapted to be energized from a conventional 110 volt 60 cycle line. Additional secondary windings H5, H8 and II'! are provided. Winding IIl supplies current to energize the heaters of the various vacuum and gas tubes in the system.

Referring now to junction 80, wire I20 runs from this junction to junction I 2I. From junction I 2| wire I22 goes to movable contact I23 of a switch. Connected to wire I22 is a bias potential generating system. Thus from wire I22, a connection is made by wire I25 to terminal I28 of transformer secondary II8. Transformer secondary II8 has its other terminal I21 connected through limiting resistor I28 to junction I30. Between junction I30 and terminal I28 of the transformer secondary is connected condenser I3I. Between wire I22 and junction I30 is connected resistor I32 and rectifier I33 in series. Junction I34 between rectifier I33 and resistor I32 is connected through resistor I35 to junction I38. Between junction I38 and wire I22 is connected resistor I31. Wire I38 connects Junction I38 and fixed contact I40 cooperating with movable contact I23 of a switch. Wire I38 is con- I nected by wire I39 to control grids I40 and I 40a of a pair of grid controlled gas tubes HI and I4Ia respectively. These two tubes have cathodes I42 and HM respectively, these two cathodes being connected to wire I43 going to a common terminal on secondary winding H5 and H8. These cathodes are also connected by wire I44 to bridge point I00.

Tube I has anode I48 connected through motor winding I 4'! and wire I48 to the outside terminal of secondary winding II5. Similarly, I4Ia has anode I45a connected through motor winding I4'la to the outer terminal of secondary winding II8 by wire I48a. Windings I41 and I4Ia are two of the windings of motor I50. Motor I50 may be of an alternating current type having means for controlling the direction of rotation of the motor. Thus for example, windings I41 and la may be shading windings for an induction type motor having the usual field winding supplied by a. single phas alternating current. Inasmuch as such reversible motors are well known in the art, a detailed showing is not made. Motor I50 may have suitable speed-reduced mechanism associated therewith and is mechancially connected to the control for adjusting the value of resistor I02 of the bridge.

Junction I2I is connected by wire I5I to switch.

I52 and thence to control grid I54 of grid controlled gas tube I55 of a type similar to tubes HI and la. Tube I55 has anode I58 connected by wire I51 to one terminal of winding I58 for controlling the position of brine valve I4. The other terminal of winding I58 is connected to wire I48a.

Returning to grid I54, grid resistor I8I is connected to cathode I82 of tube I55 and is also connected to wire I44.

The operation of the system is as follows: Assume that the various switches are in the positions shown and that the system is energized. Also assume that ham II on scale I0 has been weighed and the base weight determined by the scale mechanism. Condenser plates I5a and I5b will be in a certain position and as a result alternating current having a certain peak value will be impressed upon control grid 81 of amplifier 88. The peak value of this alternating potential will be in direct proportion to the base weight of the ham.

The output of tube 88 is amplified by tube and the resulting output is impressed on bridge point 8| through coupling condenser 08. These currents pass through the bridge to point 82. At the same time, potential from secondary III is impressed across bridge points and 82. It will be evident that for certain fixed potentials applied as above, it will be necessary to have the bridge arm resistances (or reactances for nonresistive arms) in proper relation to obtain bridge balance across points 8| and I00. Any unbalance of these points is utilized in a Servo system.

Thus the potentials at point 9| are applied to control grids I40 and H00. of tubes HI and I4Ia. The potentials at point I80 are applied to cathodes I42 and I42a of these tubes. Alternating potentials from windings H5 and H8 are degrees out of phase at anodes I48 and Mia respectively. When bridge points 3| and I 00 are out of balance the alternating potentials are also out of phase. Hence if the bridge unbalance is in one sense, the potential at one of the grids of tubes HI and la will be in phase with one anode potential and out of phase with the other anode potential. Thus either tube I or I4Ia will fire, depending upon the sign of bridge unbalance. Motor I50 will turn in one direction or other and vary bridge resistor I02 till balance is obtained. Under conditions of bridge balance, tubes HI and I 4Ia will both be in the same condition, non-firing, and motor I50 will be inoperative.

Now the switches are operated. Movable contact I04 is changed to engage contact I08. This unbalances the bridge and requires a predetermined proportional change in potential at bridge point 8| to reestablish bridge balance. This change in potential will be in a direction resulting from an increase in the ham weight although the sign could be reversed for other processes. The amount of change is proportional to the origaseraos inal balancing potential corresponding to the base weight of the ham.

Movable contact H3 is moved from fixed contact I40. Thus a negative bias potential due to rectifier I33 is impressed through wires I38 and I39 upon the control grids of gas tubes Mi and Illa. This bias is suilicient to lock tubes ME and Illa to non-firing and thus prevents resistor m2 from varying.

Movable contact 152 is closed against contact M3. The bridge unbalance is such that grid ltd has its potential raised to cause firing in tube H5. The space current through the tube and winding I58 opens the brine valve and ham pumping begins. When the ham weight has increased by the desired percentage, the resulting balance of the bridge causes tube 555 to stop firing and permit the normally closed valve to shut off the brine. The switches are returned to the position shown and the ham removed. It is understood that automatic means coupled to the valve control may be provided for returning the switches to the position as shown.

Instead of a variable condenser for modulating an alternating current in proportion to the ham weight other means may be used. Thus there is available a photo cell whose interelectrode space has an alternating magnetic field. A modulation action similar to a magnetron is obtained with the cell output being in the form of an alternatin current whose peak value may be controlled by light falling upon the cathode. The scale platform may have means for controlling the amount of light falling upon the cathode in a manner disclosed in my copending application filed concurrently with this.

I claim:

1. In a weighing system in which the article being weighed is subject to processing causing a change in weight and in which the processing is to be terminated after said article has changed weight by a predetermined percentage of its base weight, the combination of means for generating a potential whose value is proportional to the weight of said article, a second source of potential having a substantially constant value, a bridge having four arms, at least two arms of which contain substantial resistance, means for impressing the generator output and the potential from said second source upon said bridge at different portions thereon, means for varying resistance in the bridge to balance the bridge for a base weight potential of said generator against the output of said second potential source, means for unbalancing said bridge by changing resistance in the bridge by a predetermined amount, means responsive to said bridge unbalance for initiating processing of said article, and means responsive .to a condition of bridge balance for terminating the processing, said other bridge arm being un balanced enough and in such direction as to require the generator potential to change by a predetermined proportion of the base weight. potential.

2. In a weighing system in which the article to be weighed is subject to processing causing a change in weight and in which the processing is to be terminated after the base weight of said article has changed by a predetermined percentage, the combination of means for generating a potential whose value is proportional to the weight of said article, a second source of potential, said second source providing a substantially constant potential, 9. bridge having four arms with resistance in each arm, means for impressing said two potentials upon said bridge at different parts so that said bridge may be balanced, means eiiective prior to any processing of said article for varying the resistance in one bridge arm to bring said bridge to a condition of balance with the generator output potential having a value corresponding to the base weight of the article. means for varying a bridge arm by a predetermined percentage of resistance to throw the bridge out of balance, means responsive to bridge unbalance for initiating processing of said article, said bridge unbalance being in a direction such that the change of weight during article processing will cause the generator potential to vary toward a bridge balancing value and means for terminating said processing when said bridge has reached balance.

3. In a weighing system in which the article being weighed is subject to processing causing a change in weight and in which'the processing is to be terminated after said article has changed weight by a predetermined percentage of its base weight, the combination of means for generating a potential whose value is proportional to the weight of said article, a second potential source having a substantially constant output potential, a bridge having substantial resistance in at least two arms, means for impressing said two potentials upon said bridge at different parts thereof so that the bridge has a balance point for any two values of potential, means responsive to bridge unbalance for varying the resistance in one bridge arm to balance said bridge when the generator potential is at a value corresponding to the base weight of the article prior to processing, means for locking said resistance varying means, means for changing the resistance in another bridge arm by a predetermined proportion and thus throw the bridge out of balance, the sense of unbalance being such that the change in generator potential during article processing tends to bring the bridge into a condition of balance, and means for terminating the processing after said bridge has reached balance during processing.

4. The system according to claim 3 wherein the means responsive to bridge unbalance for varying the resistance in one bridge arm includes a Servo means.

5. The system according to claim 3 wherein the means responsive to bridge unbalance for varying the resistance in one bridge arm includes a pair of grid controlled gas discharge tubes and Servo means.

6. The system according to claim 3 wherein the means responsive to bridge unbalance for varying the resistance in one bridge arm includes a pair of grid controlled gas discharge tubes and Servo mechanism and wherein the means for locking said resistance varying means comprises a means for impressing a bias upon both grid controlled gas tubes to prevent operation of the Servo means.

GEORGE W. REILLY, JR.

Number Name Date Reichel Nov. 13, 1945 

